ON PHYSICAL AND ENGINEERING FEATURES OF THE MERSEY 561 
narrow, and consequently docks on the Alexandra system, of a great 
trunk with branches, could not be laid out; but the Harrington and 
Toxteth take the form of long docks of ample width, and are provided 
with sheds of the most modern type, double storey, of moderate width, on 
the eastern quays, and single storey, of exceptionally great width, on the 
western. The Union Dock forms a connecting link between the new 
deep-water dock and the older group having comparatively shallow sills. 
The total area of the docks from Herculaneum to Union inclusive is 
32 acres, 3,348 square yards, and the quayage 8,518 lineal feet, and the 
Parliamentary Estimate for the works was 1,408,640/. 
At night the entrances and passages throughout the new north and 
south systems are lighted at tide-time by electric lights raised on tall 
lattice masts, placed on the pierheads and standing 80 feet above the 
quay level; these being amongst the first introduced into England or 
elsewhere for dock purposes, as far as the Author knows. 
The sills of the older docks immediately north of the Union Dock, and 
extending as far north as George’s Dock, are laid at a level of about 
six feet below datum—six feet higher than the Herculaneum- Union group. 
These older docks could not, on neap tides, be available for vessels of, 
say, more than 16 feet draught, and could therefore not be safely used on 
neap tides by deep-draught modern vessels. To meet this ditticulty, the 
Author arranged that on such tides the water in the shallow group should 
be impounded at such a level as to afford ample draught for all vessels, the 
only disability from which they would suffer, and this is only of a trifling 
nature, being that, if required to pass between river and docks on neap 
tides, they would have to do so by way of the deep-water river entrances 
at Herculaneum Dock, the Union Dock being used as a lock between the 
old and new groups of docks. Inasmuch as there is a considerable 
loss of water by leakage at dock gates, and culverts, and for filling graving 
docks, such Joss must be made good if the water is to be maintained at a 
constant level, and this is done by means of a powerful installation of 
centrifugal pumps, situate at the Coburg Dock, which are used to pump 
water from the River Mersey into the Coburg Dock, from which it dis- 
tributes itself throughout the system. By these means the effective depth 
of the whole of the docks from Brunswick to George’s, having an area 
of about 80 acres, is practically increased to that of the lowest sills 
leading to them, 12 feet below Old Dock Sill, and much detention of 
vessels and consequent loss are avoided, which could not be done in any 
other way, except by the reconstruction of the old docks, the cost of which 
would be immense, while that of the pumps is moderate, say, some 3,000/. 
per annum. 
A pumping scheme of this character was first adopted by the Author 
in the case of the Sandon Graving Docks, of which there is a group of 
six, opening out of the Sandon Dock, constructed in 1851, and which, owing 
to the increase in the draught of ships, which prevented them entering 
the shallow graving docks on neap tides, had become much less useful to 
the Port than they formerly had been. Pumps were therefore provided 
of sufficient power to raise the water in the docks to such height as might 
be required by any individual ship, to pass her over the sill of any of the 
graving docks, and so the graving docks were made fully available for 
any ship which could enter the dock from which they opened, the sill of 
which was much lower than those of the graving docks. The success of 
this experiment warranted the extension of the system, and so it was 
1896, 00 
